1. Field of the Invention
The present invention generally relates to wireless communication, and more particularly to a radio design with infrared (IR) wireless modulation and interface capability.
2. Description of the Related Art
In the field of point-to-point data transfer, designing radio frequency (RF) communications subsystems to operate in modern computers presents many challenges and problems for engineers. For example, conventional RF solutions often employ Personal Computer Memory Card International Association (PCMCIA) adapters which are costly even before factoring the expense of the RF transceiver hardware.
Some new RF links are in development (e.g., xe2x80x9cBlueToothxe2x80x9d(copyright) from Ericsson and Nokia) which promise to be inexpensive. However, in order to be integrated into current laptop and desktop computer systems these new links require new hardware and software to be developed and distributed.
Thus, even though the above-mentioned new RF links (e.g., BlueTooth(copyright)) may have a lower cost once in production as compared to existing RF communication links, these new communication links require considerable development time and expense to be integrated into present laptop and desktop computer systems.
Furthermore, while there have been efforts to provide lower cost RF links, these efforts have xe2x80x9cover-designedxe2x80x9d or xe2x80x9cover-specifiedxe2x80x9d the links, thereby requiring new hardware and/or software to operate. Thus, hitherto the present invention, the leveraging of existing infrastructure (e.g., hardware and software already developed and used by the IR wireless industry) has not been possible, and thus such new links have been expensive and cumbersome to implement.
Other problems include that the current IR wireless solutions require aiming (e.g., aligning) the two devices. Also, IR solutions do not work well in sunlight.
In view of the foregoing and other problems, drawbacks, and disadvantages of the conventional systems, an object of the present invention is to provide an RF communication subsystem with an IR interface for use in a computing device.
In a first aspect of the invention, an apparatus for data transfer using radio frequency (RF) energy, includes a first software application that sources and links the data transfer, a second software application for controlling a communications hardware for the data transfer, a hardware device for formatting the data and gaining access to a media, and a physical layer interface hardware, coupled to selectively receive a signal representing the data from the hardware device and to provide an output to the hardware device, for sending and receiving a radio frequency communication.
With the present invention, an RF transceiver is employed which can be directly modulated with an Infrared Data Association (IrDA) modem and software hierarchy used currently in the vast majority of laptops, desktops, and Personal Data Assistants (PDA). A direct benefit of using the existing modem and software hierarchy is that implementation costs and time are minimized.
The invention overcomes the shortcomings of the related art by replacing the IR transceiver with an RF transceiver having the necessary characteristics.
While the described embodiment of the invention uses IrDA modulation to send and receive data over a 900-MHZ RF link, any RF frequency can be used, provided the RF transceiver can be modulated directly with Return-to-Zero Inverted (RZI), or Non-Return-to-Zero Inverted (NRZI) data.
Additionally, an embodiment of a radio incorporating the present invention provides a variable transmit bandwidth and therefore variable data rates as permitted by the IR stack. This configuration produces a radio having a low cost to effectively compete with proposed wireless systems.
It is noted that, while a non-limiting embodiment of the present invention is described with regard to direct application of the IR Non-Return Zone (NRZ) waveform to the RF module and the exemplary systems specify FM (or more aptly frequency-shift keying (FSK) systems), virtually any modulation scheme may be used with the present invention. Thus, for example, modulation schemes may include amplitude modulation (AM), frequency modulation (FM), X-phase shift keying (xe2x80x9cXxe2x80x9d-PSK) where X is the number of possible phases (e.g., 16-PSK has one of 16 possible values, with each time interval allows 4 bits to be transferred), M level-Quadrature Amplitude Modulation (M-QAM), etc.
Additionally, in a further embodiment, interface modules can be added between the IR and RF interface to modify the NRZ signal to any suitable form.
In another embodiment, the NRZ signal from the IR module is extracted and used as an input to an FM or FSK radio. Even when the radio is not tuned to this function, it can demonstrate the principle directly up to 56 Kbps. The limiting factor in such an embodiment is the Voltage Control Oscillator (VCO) and receive filters.
Thus, with the invention, an RF transceiver is employed which can be directly modulated with the IrDA modem and software hierarchy used currently in the vast majority of laptops, desktops, and PDAs. Thus, by using the existing modem and software hierarchy, implementation costs and time are minimized.